• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1228-1237
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• 2023

The CRISPR-Cas system has emerged as the most efficient genome editing technique for a wide range of cells. Delivery of the Cas9-sgRNA ribonucleoprotein complex (Cas9 RNP) has gained popularity. The objective of this study was to develop a quantitative polymerase chain reaction (qPCR)-based assay to quantify the double-strand break reaction mediated by Cas9 RNP. To accomplish this, the dextransucrase gene (dsr) from Leuconostoc citreum was selected as the target DNA. The Cas9 protein was produced using recombinant Escherichia coli BL21, and two sgRNAs were synthesized through in vitro transcription to facilitate binding with the dsr gene. Under optimized in vitro conditions, the 2.6 kb dsr DNA was specifically cleaved into 1.1 and 1.5 kb fragments by both Cas9-sgRNA365 and Cas9-sgRNA433. By monitoring changes in dsr concentration using qPCR, the endonuclease activities of the two Cas9 RNPs were measured, and their efficiencies were compared. Specifically, the specific activities of dsr365RNP and dsr433RNP were 28.74 and 34.48 (unit/㎍ RNP), respectively. The versatility of this method was also verified using different target genes, uracil phosphoribosyl transferase (upp) gene, of Bifidobacterium bifidum and specific sgRNAs. The assay method was also utilized to determine the impact of high electrical field on Cas9 RNP activity during an efficient electroporation process. Overall, the results demonstrated that the qPCR-based method is an effective tool for measuring the endonuclease activity of Cas9 RNP.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.475-482
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• 2007

Mobile nodes in ad-hoc wireless networks play roles of router as well as host. Movement of nodes causes network topology changes, which make existing routing information be modified. Therefore many routing protocols for ad-hoc networks were suggested in the literature. In this paper, we suggest an enhanced automatic route shortening method for dynamic source routing(DSR) protocol. DSR is a request/response based protocol which has low routing overhead owing to node movement. The current automatic route shortening is performed on the only nodes which belong to the source route of packets. On the contrary, our suggested method allows all neighbor nodes hearing the packet to participate in automatic route shortening. It makes all possible route shortenings be performed. So we maintain maximal shortened routes of ongoing data connections. Simulation results with ns2 show that our method pays small extra protocol overhead for ARS, but increases the ratio of successful packet transmissions and the number of ARSs performed in our mechanism is from 2 to 5 times higher than in original ARS mechanism and therefore it will improve the network-wide energy consumption in wireless ad-hoc networks.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.545-549
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• 2003

After irradiation of a cloned dextransucrase gene (dsrB742) with ultrasoft X-ray, an E. coli transformant (pDSRB742CK) was first developed for the expression of an extracellular dextransucrase, having increased activity and the synthesis of a highly branched dextran. Seven nucleotides of the parent gene (dsrB742) were changed in the nucleotide sequences of dsrB742ck. Among them, four nucleotides were changed at the ORF of dsrB742, resulting in a 30 amino acids deletion in the N-terminal of DSRB742 dextransucrase. The activity of DSRB742CK dextransucrase in culture supernatant was approximately 2.6 times higher (0.035 IU/ml) than that of the DSRB742 clone. The pDSRB742CK clone produced DSRB742CK dextransucrase when grown both on a sucrose medium (inducibly) and on a glucose medium (constitutively). The DSRB742 clone did not produce dextran constitutively on a glucose medium. DSRB742CK dextran had 15.6% branching and 2.7-times higher resistance to dextranase hydrolysis compared to DSRB742 dextran. $^{13}C-NMR$ showed that DSRB742CK dextran contained ${\alpha}-(1{\rightarrow}3)$ branch linkages that were not present in DSRB742 dextran.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.8-12
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• 2016

Effects of conventional rolling(CR) and differential speed rolling(DSR) on the microstructure and mechanical properties of Cu-Ni-Si alloy were investigated in detail. The copper alloy with thickness of 3 mm was rolled to 50 % reduction at ambient temperature without lubricant with a differential speed ratio of 2:1. The conventional rolling in which the rolling speed of upper and lower rolls is identical was performed under identical rolling conditions. The shear strain introduced by the CR showed positive values at positions of upper roll side and negative values at positions of lower roll side. However, it showed zero or positive values at all positions for the samples rolled by the DSR. The microstrucure and texture development of the as-rolled copper alloy did not show any significant difference between CR and DSR. The tensile strength of the DSR processed specimen was larger than that of the CR processed specimen. The effects of rolling methods on the microstructure and mechanical properties of the as-rolled copper alloy are discussed in terms of the shear strain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.542-558
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• 2016

Vehicular Ad Hoc Networks (VANETs) are self-configuring networks where the nodes are vehicles equipped with wireless communication technologies. In such networks, limitation of signal coverage and fast topology changes impose difficulties to the proper functioning of the routing protocols. Traditional Mobile Ad Hoc Networks (MANET) routing protocols lose their performance, when communicating between vehicles, compromising information exchange. Obviously, most applications critically rely on routing protocols. Thus, in this work, we propose a methodology for investigating the performance of well-established protocols for MANETs in the VANET arena and, at the same time, we introduce a routing protocol, called Genetic Network Protocol (G-NET). It is based in part on Dynamic Source Routing Protocol (DSR) and on the use of Genetic Algorithms (GAs) for maintenance and route optimization. As G-NET update routes periodically, this work investigates its performance compared to DSR and Ad Hoc on demand Distance Vector (AODV). For more realistic simulation of vehicle movement in urban environments, an analysis was performed by using the VanetMobiSim mobility generator and the Network Simulator (NS-3). Experiments were conducted with different number of vehicles and the results show that, despite the increased routing overhead with respect to DSR, G-NET is better than AODV and provides comparable data delivery rate to the other protocols in the analyzed scenarios.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.87-97
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• 2009

A Mobile Ad hoc Network (MANET) is characterized by multi-hop wireless connectivity, frequently changing network topology with mobile nodes and the efficiency of the dynamic routing protocol plays an important role in the performance of the network. In this paper, the performance of five routing protocols for MANET is compared by using OPNET modeler: AODV, DSR, GRP, OLSR and TORA. The various performance metrics are examined, such as packet delivery ratio, end-to-end delay and routing overhead with varying data traffic, number of nodes and mobility. In our simulation results, OLSR shows the best performance in terms of data delivery ratio in static networks, while AODV has the best performance in mobile networks with moderate data traffic. When comparing proactive protocols (OLSR, GRP) and reactive protocols (AODV, DSR) with varying data traffic in the static networks, proactive protocols consistently presents almost constant overhead while the reactive protocols show a sharp increase to some extent. When comparing each of proactive protocols in static and mobile networks, OLSR is better than GRP in the delivery ratio while overhead is more. As for reactive protocols, DSR outperforms AODV under the moderate data traffic in static networks because it exploits caching aggressively and maintains multiple routes per destination. However, this advantage turns into disadvantage in high mobility networks since the chance of the cached routes becoming stale increases.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.13-20
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• 2022

Basically Mobile Ad Hoc Network (MANET) is an autonomous system with the collection of mobile nodes, these nodes are connected to each other by using wireless networks. A mobile ad hoc network poses this quality which makes topology in dynamic manner. As this type of network is Ad Hoc in nature hence it doesn't have fixed infrastructure. If a node wishes to transfer data from source node to a sink node in the network, the data must be passed through intermediate nodes to reach the destination node, hence in this process data packet loss occurs in various MANET protocols. This research study gives a comparison of various Mobile Ad Hoc Network routing protocols like proactive (DSDV) and reactive (AODV, DSR) by using random topology with more intermediate nodes using CBR traffic. Our simulation used 50, 100, and 150 nodes variations to examine the performance of the MANET routing protocols. We compared the performance of DSDV, AODV and DSR, MANET routing protocols with the result of existing protocol using NS-2 environment, on the basis of different performance parameters like Packet Delivery Ratio, average throughput and average end to end delay. Finally we found that our results are better in terms of throughput and packet delivery ratio along with low data loss.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.165-173
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• 2011

In Mobile Ad-hoc Network(MANET), mobile nodes are operated by limited batteries. Therefore, it is very important to consume the battery power efficiently to prevent termination of the network. In this paper, we propose Energy-aware Dynamic Source Routing(EDSR) which is based on the Dynamic Source Routing(DSR) to increase the packet transmission and lifetime of the network. If the battery power of a node reaches threshold level, then the node gives up the function of relaying to save battery power except as a source and a destination node. While the conventional DSR doesn't consider the battery consumptions of the nodes, EDSR blocks the nodes from relaying whose battery powers are below the threshold level. Simulation results show the proposed EDSR is more efficient in packet transmission and network lifetime through the balanced battery consumption of the mobile nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1565-1570
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• 2014

In networking communication, nodes and base station send data to each nodes and destination nodes. In this perspective, it is very important to determine the direction in which data sent to each nodes or destination nodes. Ad-hoc routing protocol is a standard routing protocol that determines how the packets sent to destination. Ad-hoc routing protocol includes protocols such as Ad-hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). In our efficient proposed protocol based on small end-to-end sequence numbers, route direction can be changed properly with the assistance of helper nodes. In this paper, we focus on the simulation analysis of proposed protocol and comparison with other routing protocol models such as AODV and DSR. We simulated using Network Simulator (NS-2) by parameters such as simulation time, number of nodes and packet size based on our metrics (packet delivery fraction, routing load, data throughput). Our proposed protocol based on small end-to-end sequence numbers shows better performance and superior to other two protocols.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.322-324
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• 2005

이질적인 노드들로 구성된 이동 애드 혹 네트워크는 상이한 전송 능력을 가진 노드들로 구성되는 특성물 가지고 있다. 이런 특성으로 인해, 이질적인 노드들 즉, 높은 전송능력을 가진 노드와 낮은 전송능력을 가진 노드간에 단방향 링크가 형성된다. 하지만 현재까지 MANET WG에서 제안되어온 애드 혹 라우팅 프로토콜들은 단방향 링크문제를 명확히 해결하지 못하고 있다. 본 논문에서는 기존 DSR 라우팅 프로토콜이 단방향 링크를 지원할 때 생기는 문제점들을 설명하고 이를 극복하기 위한 새로운 라우팅 프로토콜을 제안한다.